1. The Field of the Invention
The present invention relates to systems, apparatus, and methods for curing optical components, such as optical assembly components that may be used in an optical transceiver.
2. Background and Relevant Art
Presently, systems and methods for manufacturing certain products, such as optical products and related subcomponents, can require great care, and can take a relatively long time. For example, form factor optical transceivers (e.g., SFF, SFP, XFP, etc.) can comprise several subcomponents that require precision instrumentation, or simply exercising a high degree of care, when aligning or assembling the subcomponents together.
In particular, typical form factor optical transceivers can comprise one or more Optical Sub-Assemblies (OSA), such as a Transmitter Optical Sub-Assembly (TOSA) and a Receiver Optical Sub-Assembly (ROSA). The individual OSAs are each assembled from a variety of sub-parts prior to being assembled on a transceiver. These OSA subparts typically include an OSA barrel that has a sealed end and an open end, and an optical subcomponent that is inserted into a cavity within the OSA barrel (or “barrel cavity”). An OSA optical subcomponent typically comprises an optical transmission or reception component, such as a laser diode, or a photodiode. In some cases, these subcomponents are assembled together using specialized epoxies that can create unique constraints.
As shown in FIG. 1, for example, when assembling the optical subcomponent 102 inside an OSA barrel 108, a manufacturer typically first places an epoxy 103 inside the open portion 104 of the barrel. The manufacturer then aligns the optical subcomponent inside the open portion of the barrel cavity 104, such that the optical subcomponent 102 binds to the barrel cavity 104 inner walls as the epoxy 103 hardens, forming a second sealed end. The manufacturer then places the combined subcomponent 102 and optical barrel 108 in an environment where the epoxy can be cured. Once the manufacturer has cured the epoxy 103, the manufacture can position the combined subcomponents (i.e., an assembled, cured OSA) in an optical transceiver.
Unfortunately, when an optical component is placed inside an optical barrel containing epoxy, a small amount of air (e.g., space 106) becomes trapped between the optical subcomponent and the first sealed end of the barrel cavity. Ordinarily, the air pocket 106 does not pose a substantial problem if the epoxy 103 hardens at room temperature. If a manufacturer raises the temperature too quickly, however, such as raising the temperature to a temperature that is greater than room temperature, the epoxy 103 can become less viscous (more fluid) at the same time that the air expands.
In one scenario, air expansion may force the less-viscous epoxy to ooze out of the assembled OSA 117 during the curing process, such that there is insufficient epoxy to form a bond between the optical subcomponent and the OSA barrel. In another scenario, the epoxy may become less able to contain the one or more expanding air pockets 106, which can cause the optical subcomponent 102 to blow apart from the optical barrel 108. In still another scenario, the air can form one or more bubbles in the epoxy, which, when popped, can become a gap in the joint between the optical component and the optical barrel. As such, the bond is weaker between the OSA subcomponents 102 and 108; and, further, the bond is leaky—that is, not water (or humidity) tight.
There are, of course, a variety of epoxies that can be used to bond two or more OSA subcomponents together. Generally, one epoxy can be distinguished from another epoxy based on essentially two essential parts in both epoxies—the base material and the “initiator”. In particular, an epoxy manufacturer can modify the base material and initiator in order to give an epoxy, for example, different strengths, different heat resistance, different cure time, different cure method, and other related properties. Of course, one can appreciate that advantages with one epoxy property may come at the expense of disadvantages of another epoxy property. For example, an epoxy that is very strong and resilient to certain environmental factors may take tens of hours to properly cure at room temperature. Alternatively, a weaker epoxy may cure within only a few minutes at room temperature.
In general, conventional epoxies that are used in the assembly of optical subcomponents, especially Vertical Cavity Surface Emitting Laser (VCSEL) subcomponents, can take as many as between approximately 10 to approximately 20 hours to cure at room temperature. Other epoxies that may be desirable to use with certain optical applications (e.g., due to special heat resistance properties) may take up to approximately 40 hours to cure at room temperature. Unfortunately, the types of epoxies used for bonding conventional optical components—as well as the rather small, precisely aligned optical component parts—do not lend to speeding up the curing process with added heat.
Thus, conventional methods for curing epoxies in optical components often involve rather long two-step processes. In one example, a manufacturer may first let the epoxies harden to a predetermined level at room temperature. After the epoxy has hardened a specified amount, the manufacturer might then heat the epoxy to a temperature that is greater than room temperature, in order to finalize the curing process. Unfortunately, the time it takes for conventional optical epoxies to harden sufficiently at room temperature can be anywhere from approximately 12 hours to approximately 30 hours, depending in part on the heat resistance of the given epoxy.
Other conventional curing processes can reduce the overall cure time for the epoxy, but nevertheless increase the number of required production steps. For example, a manufacturer may perforate at least a portion of the OSA barrel so that air can escape. Since the manufacturer has perforated the OSA barrel, the air can escape as the air expands, such that the air does not create air bubbles in the epoxy, or does not force the epoxy out from the assembly. Thus, the manufacturer can then cure the epoxy at an elevated temperature so that the epoxy cures more quickly.
Unfortunately, perforating an OSA barrel sometimes requires an additional processing step after the OSA barrel has been manufactured. Furthermore, since perforations can open the optical subcomponents to water (or humidity) damage, the manufacturer may still need to cover the perforations in some way after the epoxy cures. This requires still another processing step. As such, perforating one or more subcomponents to release expanding air during a curing process can be fairly inefficient, or can lead to lower quality OSAs.
Accordingly, an advantage in the art can be realized with systems, apparatus, and methods for curing a large number of adhesive bonds between small components in a relatively short time. In particular, an advantage in the art can be realized with systems, apparatus, and methods that allow epoxy bonds between optical form factor components and subcomponents to cure efficiently, without requiring extra manufacturing steps.